Colicin Js

Colicin Js is a type of Colicin, a bacteriocin made by E. coli which acts against other nearby E. coli to kill them with its cytotoxic domain; its method of killing is as yet unidentified.

Synthesis and release
The operon for colicin B is encoded on a plasmid in the cytoplasm of the E. coli. This operon also encodes its Colicin Immunity Protein, Cji, to protect the cell from the cytotoxic activities of the colicin, alongside a protein to aid the release of the colicin outside the cell.

Mechanism of uptake
The receptor binding domain of the colicin binds to the outer membrane receptor CjrBC on the target cell; it is a constitutively expressed protein parasitised by the colicin. The translocation domain then recruits proteins from the Ton system to translocate the protein across the membrane and into the cytoplasm.